We have developed computer programs to assist in the analysis and interpretation of blood glucose data obtained by self-monitoring of blood glucose by patients with insulin-dependent or non-insulin dependent diabetes mellitus. These programs allow for manual data entry by keyboard, or by automatic electronic transfer of data from glucose meters equipped with clock-calendar and memory. The data are analyzed graphically and statistically. One can obtain a series of standardized reports (summary, glucose-vs.-time, glucose by time of day, glucose in relationship to meals, or by day of the week). Alternatively, one can analyze the data interactively, examining the glucose profile for a single day, or the average glucose profile for a "window" or range of time. The time course of insulin action for several of the most commonly used types of insulin, can be displayed on the same axes as the glucose profile. This can assist the physician in making decisions to adjust appropriate insulin doses or alter insulin regimens, and is also potentially useful for education of both the patient and physician.